Effect of large span asymmetric fermentation heat storage greenhouse on thermal environment,land saving and production increase

XIAO Jinxin;LI Jianming;WU Ying;The Agriculture Ministry Key Laboratory of Protected Horticultural Engineering in Northwest,College of Horticulture,Northwest A&F University;

fermentation heat storage greenhouses(GH-F);;heat storage insulation;;fermented heat;;thermal environment analysis;;greenhouse design

【Objective】 This study investigated the heat storage and preservation performance of a large span asymmetric fermentation heat storage greenhouse(GH-F) to provide new ideas and theoretical basis for future greenhouse design in China.【Method】 GH-F was designed based on the principle of solar greenhouse.The azimuth was east-west,and it was asymmetrical in north-south direction with 10 m in south and 7 m in north.The north bottom inside was equipped with a 30.0 m×1.0 m×1.0 m agricultural waste fermentation pool according to the length of the greenhouse.The experiment was compared with Chinese solar greenhouse(GH-P) and a large span double layer internal heat preservation greenhouse(GH-D).The heat dissipation of the three greenhouses under the maximum heating load(temperature difference between indoor and outdoor was 20 ℃) was compared by theoretical analysis method.The diurnal variation of illumination intensity of the three greenhouses on sunny days in winter were determined.The thermal storage,heat preservation performance,cost of investment,and benefit of land saving and production increase under typical sunny,cloudy and snowy days in winter were also compared by experimental measurement method.【Result】 Under the condition of 20 ℃ difference between indoor and outdoor at night,heat dissipating capacities of GH-F,GH-D and GH-P were 51.21,45.99 and 41.86 W/m~2,respectively.The thermal insulation performance of GH-F was less that as that of GH-D and GH-P,thus heat was needed to be supplemented by fermentation pool.The average temperature of the fermentation pool was 24.7 ℃,higher than the indoor temperature from January 01 to January 31,2016,which effectively released heat to the inside.The average night air temperatures of GH-F,GH-D and GH-P on a typical sunny day were 7.9,5.0 and 8.0 ℃ and ground temperatures were 12.0,10.4 and 10.7 ℃.The average night air temperatures of GH-F,GH-D and GH-P on a typical cloudy day were 8.7,5.8 and 7.3 ℃ and ground temperatures were 11.3,9.1 and 10.9 ℃.The average night air temperatures of GH-F,GH-D and GH-P were 8.9,6.5 and 7.1 ℃ and ground temperatures were 11.6,9.8 and 9.3 ℃ on a typical snowy day.During the whole experimental period,the average daily air temperature of GH-F was 2.1-3.0 ℃ higher than that of GH-D and 0.7-2.1 ℃ higher than that of GH-P.The average daily ground temperature of GH-F was 1.4-2.0 ℃ higher than that of GH-D and 0.5-2.2 ℃ higher than that of GH-P.Under extreme outdoor temperature of-14.3 ℃,the lowest night temperature of GH-F was 5.4 ℃,which was 3.8 and 0.8 ℃ higher than that of GH-D and GH-P,respectively.The final benefit analysis showed that the construction cost of GH-F was 180.06 yuan/m~2,59.97 and 170.02 yuan/m~2 lower than GH-D and GH-F.GH-F increased land utilization rate by 29.93% and increased tomato yield by 1.80 kg/m~2 in comparison with GH-P.【Conclusion】 The design of GH-F was reasonable with better temperature performance,land utilization rate and actual planting effect than GH-P.It is suitable for the popularization and application in the middle and lower reaches of the Yellow River and the Huai River Basin.